Fixing device

ABSTRACT

A mounting device for attaching a fuel injector both to a cylinder head of an internal combustion engine and to a fuel distribution line, includes two spring tongues which are insertable into a holding groove of the fuel injector or the fuel distribution line. A distance between the tips of the spring tongues is smaller than the largest diameter of the opening surface enclosed by them, and the spring tongues are radially elastically displaced with respect to an axis of the fuel injector. At least two spring elements, elastically displaced in the axial direction with respect to the spring tongues by either tensile or compressive forces, are formed and are axially non-positively, detachably connectable to the opposite fuel injector or the fuel distribution line via a catch connection.

FIELD OF THE INVENTION

The present invention relates to a mounting device for attaching a fuelinjector to a cylinder head of an internal combustion engine, as well asfor connecting the fuel injector to a fuel distribution line.

BACKGROUND INFORMATION

German Published Patent Application No. 29 26 490 refers to a mountingdevice for mounting a fuel injector on an intake manifold, where amounting element axially attaches the fuel injector to the fueldistribution line or to a plug nipple. The mounting element is designedas a U-shaped securing clamp having two legs which are elastic in theradial direction. In the assembled state, the securing clamp engagescorresponding recesses of the plug nipple and is snappable in a recessin a connection fitting of the fuel injector, the recess being designedas a ring groove. The axial clearance between the recesses and thesecuring clamp, as well as between the ring groove and the securingclamp, should be kept small in order to achieve accurate attachment ofthe fuel injector without stresses on the gasket.

A disadvantage of the mounting device referred to in German PublishedPatent Application No. 29 26 490 C2 is the fact that hold-down forcesmay only be transferred to a limited extent. In particular, it is notpossible to produce a relatively uniform hold-down force along a certainaxial length in order to compensate positional tolerances. GermanPublished Patent Application No. 29 26 490 C2 only relates to an intakemanifold injection system, thus offering no solution on how positionaltolerances in high pressure fuel distribution lines may be compensated.

SUMMARY OF THE INVENTION

The mounting device for a fuel injector according to the presentinvention provides for positional tolerances, in particular axialpositional tolerances, between the fuel injector and the fueldistribution line which may be compensated by further stressing thespring elements. Using the spring elements, the fuel injector is helddown in the cylinder head by a hold-down force when the fueldistribution line is mounted on the cylinder head and is pushed towardthe cylinder head. From a rest position, the spring elements arestressed by axial pressure which provides a hold-down force on the fuelinjector.

Furthermore, by using the mounting device, the fuel injector may beconnected to the fuel distribution line as early as at the time of theassembly and may be removed complete in one unit composed of themounting device, the fuel injector, and the fuel distribution line atthe time of each disassembly. The spring elements are under tensilestress and the mounting device is able to pull the fuel injector out ofthe cylinder head since the catch connections, as well as the springtongues in the holding groove, transfer tensile and compressive forces.

Screws or securing clamping claws for mounting on the front face of thecylinder head are avoided by using the mounting device according to thepresent invention.

The catch connections may be formed by recesses in a section of thespring elements into which the catches of the fuel injector or the fueldistribution line are insertable. Due to the radial elastic force of thespring elements, this embodiment may snap in, requiring no additionalcomponents.

In another embodiment, the spring elements may have a fold facingradially outward. The bent section of the spring elements allowsinfluencing either the tensile or compressive spring constants.

The mounting device may be made of injection-molded plastic.

Alternatively, the mounting device may be made of spring sheet metal andmanufactured as a punched piece being subsequently bent to shape. On theside facing the holding groove, the spring tongues, at least in apartial section, may be axially bent so that the tongues may be fastenedin an axially elastic manner without play during insertion into theholding groove.

The two alternatives allow for cost-effective manufacturing methods.

The holding groove may be formed on the fuel injector. The catchingconnection may be formed on the fuel distribution line. The mountingdevice in the holding groove requires the smaller overall height and maytherefore be mounted on the fuel injector.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the present invention are illustrated in thedrawing in a simplified form and are explained in greater detail in thefollowing description.

FIG. 1 is a perspective view of a first exemplary embodiment of amounting device according to the present invention.

FIG. 2 is a schematic sectional view of the exemplary embodiment of FIG.1 in a mounted position on a fuel injector and a fuel distribution line.

FIG. 3 a is a second exemplary embodiment of a mounting device in aschematic detail section.

FIG. 3 b is a third embodiment of a mounting device in a schematicdetail section.

FIG. 3 c is a fourth exemplary embodiment of a mounting device in aschematic detail section.

DETAILED DESCRIPTION

FIG. 1 is a perspective view of a first exemplary embodiment of amounting device 1 according to the present invention for a fuel injectorto be mounted on a fuel distribution line. Two spring tongues 2 areformed on mounting device 1, the spring tongues having an openingsurface of a maximum diameter d2 between them. This opening surface ispositioned perpendicularly to an imaginary axis 3 which is identical toan axis of symmetry of the fuel injector.

Spring tongues 2 have a distance d1 between tips which is smaller thandistance D2. Mounting device 1 may be mounted on the fuel injector usingspring tongues 2 which are insertable into a holding groove. This allowslateral slip on mounting device 1. This-causes a friction-type lockingin the longitudinal direction of axis 3. In the present exemplaryembodiment, spring tongues 2 are joined by two spring elements 4 whichmay be elastically displaced in the direction of axis 3, either bytensile or compressive forces.

The mounting device in its relieved state, i.e., no force acts on springelements 4, is illustrated in FIG. 1. Recesses 6 are situated in contactsections 5 of spring elements 4. The fuel distribution line may havecorresponding catches which may lock into the recesses. This allows afriction-type locking with the fuel distribution line in thelongitudinal direction of axis 3. Radially with respect to axis 3,spring elements 4 have fold area 7 whose folds, in the present example,have a sharp-edged design. In an edge area 8, spring tongues 2 areslightly bent.

With respect to the longitudinal direction of axis 3, spring elements 4have one spring constant for a force which is trying to increase thedistance of recesses 6 vis-a-vis spring tongues 2, as well as a secondspring constant for a force which is trying to reduce this distance.Thus, in a certain elasticity range, forces may be transferred betweenrecesses 6 and spring tongues 2 by both pulling and compression in thedirection of axis 3 with an intermediate neutral area.

FIG. 2 is a schematic sectional view of the exemplary embodiment of FIG.1 in the mounted position for a fuel injector 9 mounted on a fueldistribution line 10. With an end section 11, fuel injector 9 isinserted in a location hole 12 of fuel distribution line 10. An O ring13, which is supported by a support ring 14, seals end section 11against location hole 12. The fuel flows toward location hole 12 via abore 15. With its recesses 6, mounting device 1 is locked in catches 16on fuel distribution line 10. The mounting device is depictedsectionally in the plane of section defined in FIG. 1 by line 2 and axis3. Spring tongues 2 including edge area 8, which is slightly bent, areinserted into holding groove 17 which is formed on fuel injector 9. Therespective folding areas 7 of both spring elements 4 are positionedradially outwards. The parts of spring elements 7 upstream anddownstream of folding area 7 are no longer positioned parallel sincefuel distribution line 10 exerts a pressure force on fuel injector 9 inthe direction of the flow direction of the fuel, the pressure forcebeing transferred from catches 16 to holding groove 17 by mountingdevice 1. This holding force is the required hold-down force forsecurely holding the fuel injector on a cylinder head against thepressure of a combustion chamber. Bent edge area 8 prevents springtongues 2 from having any play in holding groove 17, because jammingoccurs.

In the case of disassembly, fuel injector 9 and fuel distribution line10 may be removed together. If fuel distribution line 10 is pulled inthe direction opposite to the flow direction of the fuel in inflow bore15, each spring element 4 is pulled beyond its fulcrum and no longerexerts any pressure force on fuel injector 9. A pulling force istransferred to fuel injector 9 via holding groove 17 and fuel injector 9is pulled away from a cylinder head. It may thus be removed togetherwith fuel distribution line 10.

However, fuel distribution line 10 may be removed alone by removingmounting device 1 beforehand. This may take place by stressing contactareas 5 of spring elements 4 radially outwards to the extent that theymay be removed from catches 16. At the same time, the mounting deviceall together may be pulled out of holding groove 17, in the illustrationforward towards the viewer, by spring tongues 2 spreading wide enough sothat distance d1 in FIG. 1 becomes large enough to be pulled over thediameter of holding groove 17 into its base.

This mounting device 1 may be easily manufactured by stamping the device1 out of spring sheet metal and subsequent bending to shape. Largehold-down forces may be transferred by selecting suitable materials. Theuse of otherwise required components such as a mounting securing clampand screwing arrangements is thereby avoided.

FIGS. 3 a, 3 b, and 3 c show in schematic sections further exemplaryembodiments of mounting device 1 according to the present invention ofFIG. 1 and FIG. 2, having differing folding areas compared to foldingarea 7 of FIGS. 1 and 2. Due to the symmetry, only one side of mountingdevice 1 is illustrated. Folding area 18 a in FIG. 3 a is configured asa semicircular arch. This prevents a notch effect in the area of springelement 4. The bending moment over semicircular arch 18 a is relativelyuniform. As an example, FIG. 3 b illustrates an acute-angled foldingarea 18 b. Finally, FIG. 3 c illustrates a multiple fold 18 c in thearea of spring elements 4.

Both last-mentioned exemplary embodiments allow for a relatively lowspring constant possible.

1. A mounting device for attaching a fuel injector both to a cylinderhead of an internal combustion engine and to a fuel distribution line,the mounting device comprising: two spring tongues which are insertableinto a holding groove in one of the fuel injector and the fueldistribution line, a distance between tips of the spring tongues beingsmaller than a largest diameter of an opening surface enclosed by thetips, wherein the spring tongues are radially elastic with respect to anaxis of the fuel injector; and at least two spring elements, elasticallydisplaced in a direction of the axis with respect to the spring tonguesby one of tensile and compressive forces, the elements formed andconfigured to be axially non-positively, detachably connectable to oneof the fuel injector and the fuel distribution line via a catchconnection, wherein on a side facing the holding groove, the springtongues, at least in a partial section, are axially bent so thatclearance-free, axially elastic jamming occurs when the spring tonguesare inserted into the holding groove.
 2. The mounting device accordingto claim 1, wherein the catch connection is formed by recesses in asection of the spring elements, wherein catches of one of the fuelinjector and the fuel distribution line are inserted into the recesses.3. The mounting device according to claim 1, wherein the spring elementshave a fold radially outward.
 4. The mounting device according to claim3, wherein the fold is a multiple fold.
 5. The mounting device accordingto claim 1, wherein the mounting device is made of injection-moldedplastic.
 6. The mounting device according to claim 1, wherein themounting device is made of spring sheet metal and is manufactured as apunched piece that is subsequently bent to shape.
 7. The mounting deviceaccording to claim 1, wherein at least three spring elements areradially and uniformly arranged.
 8. The mounting device according toclaim 1, wherein the holding groove is formed on the fuel injector, andthe catch connection is formed on the fuel distribution line.